Analysis of welding-brazing joints of Ti/Al dissimilar metals obtained by cold metal transfer method

Cold metal transfer(CMT) welding-brazing of Al6061 and TA2 was carried out using ER4043 filler metal. The microstructure characteristics of the Ti/Al joints were analyzed by optical microscopy, scanning electron microscopy and energy dispersive spectrometer, respectively. Mechanical properties of the joints were characterized by measurement of the tensile strength. The results indicate that a welding-brazing joint was formed by CMT method, which included a welding joint at the aluminium sheet side and a brazing joint at the titanium sheet side. The intermetallic compound at the brazing interface consisted of two different layers. Among them, the continuous layer near titanium substrate was composed of Ti₃Al intermetallic compound, while the serration-shaped layer next to the weld metal was composed of TiAl₃ intermetallic compound. When groove angle 30° of titanium sheet was used during the welding process, uniform intermetallics would be formed at the brazing interface, thus sound joint which had a tensile strength of 197.5 MPa was obtained and the failure location of this joint was at Al HAZ.